Thursday, April 16, 2009

SkyCatcher Not Catching the Sky Properly?

Cessna introduced the SkyCatcher, a light sport plane, at Oshkosh this year, but it is not yet ready for market. Cessna had two prototypes, but both have been destroyed during flight testing. An aviation week article alerted me to the events of the second flight test accident.

It sounds like a pretty harrowing flight. The test pilot deliberately put the airplane into a spin "during a planned test condition" which I assume, possibly incorrectly, relates to a particular centre of gravity and weight combination. The entry would also have included a particular combination of flaps, power and attitude, inducing a stall with yaw, leading to a spin. The resulting spin was particularly rapid, and the proper control inputs did not cause the airplane to recover from the spin, so the test pilot activated the aircraft parachute.

It deployed correctly, and the airplane stopped spinning, so the test pilot then tried out another function of the new aircraft design: the ability to jettison the parachute and return to normal flying. But that function didn't work. Being a test pilot, he was wearing a personal parachute, too, but by the time he opened the door to use that, there wasn't enough altitude for it to open, so he landed, uninjured, with the parachuting airplane.

I'm intrigued by the NTSB investigator's statement that "surface winds inflated the parachute and drug the airplane." In standard my dialect of English, the past tense of drag is dragged but this writer has chosen "drug." I wonder if that is a regionalism.

The whole story is not a great ad for the SkyCatcher, but things going wrong in testing is why testing is necessary, and why you shouldn't fly your airplane in a non-certified condition.

And in the "ideas to save money" category, the Greater Toronto Airport Authority is talking about closing the Buttonville airport. Yes, they are considering closing the general aviation airport that keeps training, medevac and business flights out of Pearson, the busiest airport in Canada.


jinksto said...

Wow... In looking this up I found that not only is "drug" a correct simple past of "drag", but dialectically, the verb: to drug (meaning to drag) actually exists (at least according to the OED).

In the US Deep South drug is a common past tense usage. I don't know about elsewhere. It's the form that I use but, like many things, simply accepted it as a colloquialism.

It turns out that it's actually what's known as a "strong" or (apparently) incorrectly "irregular" verb.

Here's a bit of research that I found on it. The following certainly isn't my work, I can barely remember not to say aint when on conference calls:
"English has two ways of making the simple past tense and the past participle.

One is an ancient Indo-European method, called the Umlaut row. You change the vowel within the verb to indicate the simple past and the past participle. Many now call these verbs: irregular. This is a Gallicism. They are not "irregular" they are what are called in all other Germanic languages "strong." They are not "irregular" because they can all be placed in seven Umlaut rows, although, since they constitute many of the most used verbs of the language, no one bothers, because one learns them from the cradle. This method of forming the past is, however, not unique to Germanic languages. It exists in Latin as well and, although they do not recognize it as such, it still exists in French: lire (je lis), je lus (I read - simple past), lu (past participle).

The other way of making the simple past and the past participle is to add -ed to the verb stem (the infinitive or the first person present tense): walk, walked, walked. These are called "regular" by English grammars, weak by other Germanic grammars.

Over a period of years, many speakers of English (particularly Brits) have abandoned the strong forms for verbs which are not used too often and have substituted weak endings. This has also happened, though to a lesser degree, in the U.S.

But here are some pairs, explained by this same phenomenon:

I dived into the water.
I dove into the water. (Most U.S. speakers would not hesitate to say this, although most, but not all, have substituted the weak past participle for the strong. Where I grew up, however, people did not hesitate to say: After I had diven into the water, I found they had not followed me. Diven is correct. The OE forms are: diwan, daf, ydiwen, in the same Umlaut row as: drive, drove, driven, which, as far as I know, almost all English speakers still say

They have smited them all with hard blows.
They have smitten them all with hard blows.
Both are, of course, correct. The latter, however, is the older English form of the verb: smite, smote, smitten. I believe our British cousins preserve the strong past participle in sentences such as: He was very smitten with her.

Hope this explanation helps. Adopting "regular" (weak) endings is convenient, of course, and is generally not wrong, as long as usage approves it, it does, however, make reading Shakespeare, the King James Version of the Bible, and most authors through the end of the 17th century more difficult."

david said...

Long term, I know, there are plans to close Buttonville if/when the Pickering Airport ever launches (the government appropriated land for it nearly 40 years ago, at the same time as Mirabel), but it makes no sense to close it now.

The Star article omits the Oshawa Airport, which can also handle bizjets (I think), though it's a longer drive from downtown TO.

Unknown said...

Drug? Who'd have thunk?

Sarah said...

The loss of a 2nd C162 in spin testing has to be a blow for Cessna. This is not a great advertisement for a training aircraft.

Now granted, flight test regime may be extreme, but it should not be possible to put a within CG limit trainer into an unrecoverable spin. Not one I'd like to use for spin training anyway. ( I remember the "traumahawk". )

Maybe next time they will use a proper "spin chute" for recovery instead of the BRS. These are small tail-mounted drogue chutes designed to break the stall/spin, and then be cut away. It doesn't sound like jettison of the BRS works very well, and why should it?.

Colin said...

I was confused trying to transit the Buttonville airspace when I flew up from City Centre to Parry Sound. I wish there were a standard route around it or something.

Here in the States the Pearson approach controller would not have handed me off to the Buttonville tower, he would have coordinated my transition (or, more likely, used a standard route he is allowed to control me through).

zd said...


The last time I heard "smite" in a sentence was when my flight instructor on my very first flight explained that the altimeter was an important instrument to watch. If I did not look at it, he said,

"The ground shall rise up and smite thee!"

david said...

Colin: it all depends on where you're flying in the U.S. When I want to fly from Ottawa to New York City, Boston Center hands me off to Wheeler-SAC, Syracuse and Binghamton (or Burlington VT, if I take that route), even though I'm flying above or outside those terminal areas. If I'm VFR, NY approach will often just tell me to remain clear of (e.g. below) Class B until I can call Teterboro tower. When I flew around L.A., on the other hand, SoCal handled the whole thing.

Basically, air traffic control units in Canada *and* the U.S. have formal (and informal?) agreements about who's going to handle what traffic. In upstate NY, the approach controllers seem to take everything under 10,000 ft, even if it's in Center airspace. Your mileage will vary depending on what part of the country you fly in.

Frank Van Haste said...


Just for's my understanding that the parachute jettison "feature" alluded to in the article is for the testing regime only. When the airplane gets to Joe Pilot, the BRS will stay firmly attached after deployment.


Anonymous said...

Time for a little Ghandi in Toronto -- have the GA pilots at Buttonville fly over to YYZ for a cup of coffee and a sandwich at one of the FBO's, then fly back.

Adding a few dozen flights per hour at YYZ would clog the airport mightily, and be a prediction of what could happen in the future.

Do it for 5 days. Then stop. The effects of the decision now benchmarked, go ahead of make it.

From an airline operating perspective, Pearson is one of the most expensive airports in the world. Inept management is a primary cause.

As a passenger I had to transfer from one flight to another through Toronto, and the required route was to drag my bag and myself a long way in one direction, cross over some walkway, and then I drug my bag and myself all the way back in the other direction, ending up about 50 feet from where I started, on the other side of a glass wall, having walked about 400yards. There were two different stations where folks were paid to sit and look at all boarding passes that came through, making sure everyone was repositioning into the correct areas, in an apparent correction for bad design of required traffic patterns. I just looked at one of the McCheckers and asked "Excuse me, I was under the impression they designed this airport?"

david said...

Anonymous: great idea, except that YYZ has pretty-much the highest landing fees in the world: you can pay close to $200 for landing a Cessna, depending on the time of day. Then you'd have the FBO ramp fees...

They can't ban small planes (any more than you could ban small cars from the 401 to make more room for trucks), but they try very hard to price us out.

CYOW + CYVR said...

OT / @Aviatrix:

Any comment on the poor guy who jumped out of a King Air to his death today?

How could someone without superhuman strength get a (small) airliner door open at altitude?

dpierce said...

jinksto: Great information! I love the influences in our language from its various roots.

nec Timide said...


It is an interesting article, but if I remember correctly the King Air doesn't have a 'plug' door (like a 737), hence the four large pins. If I am correct, the only force needed would be to overcome the friction on the pins. Once done the pressurization would blow the door open.

The problems 747s and L1011s had with 'non-plug' cargo doors opening in flight under pressurization shows that it probably doesn't take all that much force.

GPS_Direct said...

@nec Timide

I think you meant DC-10 instead of L1011. I don't recall L1011 having door issues. At least not like the ill-fated DC-10 anyhow.

Re: C-162

I was at a training conference where Cessna was talking about the 162 as a trainer, and the mods they had made to #2. Two days later and it crashes from a spin.

On the positive side, they are running the plane through a full flight-test regime. Well beyond ASTM standards for light sport. Interesting when you realize another LSA was brought down because one aileron wasn't connected. Opposite rudder and one aileron couldn't stop a roll away from the p-factor...

We'll see how Cessna makes out. The 162 may be having issues, but they certainly seem serious about thoroughly testing it. What they say/show at Sun-n-Fun next week should prove interesting.

nec Timide said...

Right DC-10, must go get some sleep.

Aviatrix said...

Well, quick thoughts:

The King Air door, as someone already pointed out, isn't held shut by pressurization. I don't know of a reason why you couldn't work the mechanism to open it in flight just as you do on the ground, but there could be some pressure-related interlock I don't know about. When you latch the door there's a place you look through to ensure the latches are properly engaged. I guess the pressure would make it a lot harder to slide the latches.

23,000' isn't instant death of hypoxia territory. It's low oxygen territory yes, but you're not going to die before you can do something. The summit of Mt. Everest is over 29,000'. Time of useful consciousness at 23k should be about ten minutes for a healthy person, plenty of time to acknowledge the emergency, put on an oxygen mask and make a descent.

The King Air is often flown with the door removed for skydiving, so while the airstairs door may have been damaged by the slipstream and would have caused yaw the pilots would have to compensate for, it wasn't an unheard of situation.

It would have been about -40 (that's the same in C or F) at 23,000' today in Cambridge Bay. That would have been distinctly unpleasant.

david said...

Just some quick mental sums: assuming the King Air was carrying its maximum pressure differential of 6.6 psi (giving a cabin altitude of about 10,000 ft at FL230), and that the door is 5' x 2' (a wild guess), or 1,440 in^2, then there would be 9,504 lb pushing out on the door. Sounds like a lot of friction for the pins.

nec Timide said...

@david, I will trust your figures, but we would also need to know the coefficient of friction of the pins with the sockets, and the mechanical advantage of the latching system. This varies a lot depending on the materials but could be as low as 0.04 (steel pins in Teflon sockets) so the friction would be about 376lbs. Greased steel on steel seems to be around 0.15 giving 1520lbs. That seems like a lot, but if the mechanical advantage was 10:1 (the end of the handle moves through an arc of 10 inches to move the pins 1 inch) only 152lbs would be required. Certainly not super human ability. This tragedy seems to confirm that it is possible.

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